A conventional shearing apparatus comprises as shown in FIG. 10 and FIG. 11, a plurality of spiral cutter blades 36 disposed on an outer surface of a cylinder 34 and a fixed blade 37 disposed under the spiral cutter blades. Threads on a cloth 24 are sheared while the cloth passes over a shearing table 38 and relative positions of the spiral cutter blades and the fixed blade are adjustable and both the spiral blades and the fixed blades are movable upwardly and downwardly relative to the shearing table 38.
In the above described conventional shearing apparatus, to increase a shearing efficiency, it is necessary to rotate the cylinder having the spiral blades at a high speed or to increase the number of the spiral blades so that they are disposed closely to each other on the cylinder. However, when the spiral blades rotate at a very high speed, wind caused by the rotating blades blows down the threads on the cloth, such that the shearing is not accomplished over the whole cloth. While the spiral blades are disposed closely to each other, sheared threads get stuck between the blades, thereby causing problems with the machine.
Further, sheared threads float in the air, thereby harming the environment. They also stick to the blades and fall down onto the cloth thereby preventing smooth shearing.
To solve the problems of sticking, a suction nozzle near the blades is proposed but it is not a complete solution. Further, if the suction power is increased, the cloth passing over the shearing table floats up from the table such that uniform shearing is not achieved or the cloth itself is damaged.